The present invention relates to a fixation insert having improved "back riveting" ("flash-through") safety, consisting of a planar textile structure of natural and/or synthetic threads or fibers and a coating of a thermally softenable adhesive compound applied on the front of the structure.
Fixation inserts are materials with stiffening action which can be cemented to the inside or back of outer materials by a coating of adhesive compound and which impart to the outer materials the desired fashionable drape, fit and feel.
It is desirable to make fixation inserts of as light a weight as possible so as to increase the "breathing" ability of the overall material, ensure wearing comfort and minimize material costs.
Fixation inserts are provided on their surface with a layer of thermoplastically softenable adhesive compound, usually in a geometric pattern. The inserts are placed with this layer on the back of the outer material and subsequently ironed over. In the ironing process, the adhesive compound is thermally softened. It enters into an adhesive bond with the inside of the outer material, and more or less firm adhesion results after cooling.
An intended effect on the property of the outer material is possible only if the adhesion achieved between the fixation insert and the outer material is of high quality, i.e., if the amount of thermoplastic adhesive compound per unit area does not fall below a certain minimum. In the case of light weight fixation inserts, for example, those of planar textile structures with an area weight of less than 60 g/m.sup.2, considerable difficulties can arise since the required amount of adhesive compound can easily penetrate through the planar structure to the back thereof and not only dirty the ironing apparatus but can also make it stick to the planar structure. In this case, the term "back-riveting" or "flash-through" is used to describe this extremely undesirable effect.
To overcome these difficulties, it has been proposed to use only heavy weight non-woven fabrics with an area weight of, for example, more than 70 g/m.sup.2 for the production of fixation inserts. A decrease in the breathing ability of the materials, however, must be tolerated in such a case.
DE-AS No. 24 61 845 relates to a fixation insert of a woven or knit fabric or a non-woven fabric, on the top side of which a bonding agent is applied in a fine, raster-shaped print under a correspondingly large amount of adhesive compound. The bonding agent is chemically cross-linked, whereby it is unable to soften during the ironing operation. It can, therefore, block the pore structure of the planar structure during the softening of the adhesive compound and in this manner prevent the adhesive compound from penetrating through the planar structure. The application of defined amounts of the bonding agent and the adhesive compound in closely adjacent zones with a diameter of 0.5 to 1 mm in working widths of more than 1 m, however, is so trouble-prone that the manufacture of such fixation inserts on a large commercial scale is problematical.
From Krema, Handbuch der Textilstoffe, Deutscher Fachverlag GmbH, Frankfurt, 1970, page 191-192, it is known to cover a base material provided with an adhesive layer from above or below with short fibers in an electrostatic field.